Hyperthermia and hemodynamic instability 5 hours after anesthesia
43 y/o women underwent robotic hysterectomy for 5 hours. The patient has a coronary artery disease and had two previous surgeries without complications. Few hours post operatively, she became tachypnic and hypoxic slowly. The trachea was intubated but the patient’s medical status continued to deteriorate. Hyperthermia occurred 8 hours following surgery with acidosis and BE of negative 9. Patient was resuscitated with fluids and vasopressors and transferred to a university center 24 postoperatively. Rigidity or extreme hypercapnia never occurred. However, cardiac arrhythmias appeared with some cardiac dysfunction.
1) What is your diagnosis?
A- Definitely MH
B- Probably MH
C- Cardiac event
D- B&C
Thirty-six hours post operatively, the patient is requiring minimal amount of vasopressors. Urine output is adequate with clear color. CK did not rise and temperature is normal.
2) Do you think this is MH?
A- Yes
B- No
C- Need more information
3) Caffeine halothane contracture testing is indicated in all the following except?
A- Clinical history with suspicion for malignant hyperthermia
B- A first-degree relative of a patient with documented MH
C- Unexplained muscular rigidity with MH suspicion
D- Sudden cardiac arrest on induction of anesthesia
4) The most sensitive and useful monitor for the early diagnosis of a hypermetabolic event is:
A- EKG
B- Temperature monitor
C- ETCO2
D- Pulse oximeter
E- Blood pressure monitor
5) What disease(s) are associated with MH?
A- King-Denborough Syndrome
B- Minicore myopathy
C- Central Core Disease
D- All of the above
Answers
Narrative:
1) The patient presented with one of the MH classical findings, elevated temperature. Although MH cannot be ruled out yet, a cardiac event seems more probable. A cardiac event explains the arrhythmias and hemodynamic instability, but may not explain the hyperthermia. A patient with untreated MH episode will have worsening symptoms. Additionally, although it is possible for an MH episode to start hours following exposure to a triggering agent, the chances decrease as time goes by.
Answer D
2) Although the patient had some symptoms similar to MH (arrhythmias, hyperthermia, acidosis), hypercapnia, elevated CK, or rigidity did not occur. In 36 hours post untreated MH episode we expect CK to be elevated severely and urine color to be coca-cola due to sever muscle breakdown. Clear urine in this patient makes MH unlikely although globinurea can always be detected by urine analysis.
Answer B
3) Currently, the in vitro contracture test (IVCT) is the gold standard for diagnosing MH. However, the IVCT is very expensive, requires a surgical procedure that can only be performed on-site in one of approximately 10 specialized testing centers in the
Answer D
4) Early rise in ETCO2 is the most sensitive indicator of a hypermetabolic event. All other monitors help in detecting MH episode, but they are not as sensitive as ETCO2. Increase in temperature is usually a late sign although it could be the first sign in some instances.
Answer C
5) All three diseases are associated with MH as all of them have a genetic defect on the same gene (RYR1), just like MH. Patients with muscular dystrophy were previously thought to have relationship with MH as they occasionally exhibit same symptoms as MH when exposed to general anesthetic, succinylcholine in particular. We now know that theses symptoms (arrhythmia, cardiac arrest) are related to hyperkalemia and not MH.
Answer D
Assistant Professor, Anesthesiology
Children’s
